Device for periodically supplying measured quantities of a pressure fluid to a nozzle

ABSTRACT

A device for periodically supplying measured quantities of a pressure fluid to a nozzle adapted to blow a weft thread into the shed of a pneumatic loom, comprising a metering chamber fed by a pressure fluid source and connected to the nozzle through a periodically opening valve means, control means being provided to influence the behaviour of the weft thread and more particularly to stabilize the position of the weft thread in the fluid jet irrespective of the nature of that thread.

United States Patent Vermeulen Jan. 1, 1974 DEVICE FOR PERIODICALLY SUPPLYING MEASURED QUANTITIES OF A PRESSURE FLUID TO A NOZZLE [75] Inventor: Geert Jan Vermeulen, Deurne, Netherlands [73] Assignee: N.V'. Machinefabrik L. Te Strake,

Deune, Netherlands [22] Filed: Apr. 7, 1971 [2]] Appl. No.: 131,934

[30] Foreign Application Priority Data Apr. 14, 1970 Netherlands .1 7005367 [52] U.S. Cl. 139/127 P [5 l 1 Int. Cl D03d 47/28 [58] Field of Search 226/7, 97; 139/127 P, 144

[56] References Cited UNlTED STATES PATENTS 12/1953 Svaty 139/127 P Piot 139/144 Primary Examiner-Henry S. Jaudon Att0rney-Marshall & Yeasting [57] ABSTRACT A device for periodically supplying measured quantities of a pressure fluid to a nozzle adapted to blow a weft thread into the shed of a pneumatic loom, comprising a metering chamber fed by a pressure fluid source and connected to the nozzle through a periodically opening valve means, control means being provided to influence the behaviour of the weft thread and more particularly to stabilize the position of the weft thread in the fluid jet irrespective of the nature of that thread.

1 Claim, 3 Drawing Figures DEVICE FOR PERIODICALLY SUPPLYING MEASURED QUANTITIES OF A PRESSURE FLUID TO A NOZZLE BACKGROUND OF THE INVENTION The invention relates to a device for periodically supplying measured quantities of a pressure fluid to a nozzle adapted to blowa weft thread into the shed of a pneumatic loom, comprising a metering chamber fed by a pressure fluid source and connected to the nozzle through a periodically opening valve means.

In a well-known device of this type the valve means is constituted by a rotating disc controlled from the main shaft of the weaving loom, said disc having an eccentrically positioned aperture and being adapted to permit a quantity of pressure fluid to enter into the metering chamber through said aperture, thereafter to cut off the chamber from the pressure fluid source and then to put the chamber into communication through the said aperture with the nozzle so as to make the measured quantity of pressure fluid flow to the nozzle and leave the latter in the form of a jet. In this manner a strong pulse of relatively short time period is applied to the leading end of the weft thread by the jet leaving the nozzle and the weft thread will get the acceleration required to be transported in a predetermined available time along the desired distance through the shed. Usually it is desired that the nozzle bring the weft within the influence of one or more auxiliary injectors provided in the shed, which take care of the further transportation of the weft throughthe shed. Now the taking over of the leading end of the weft, set into movement by the nozzle jet, by the auxiliary injector(s) strongly depends on the behaviour of the weft when arriving at the first auxiliary injector. The more this behaviour is quiet and therefore the optimum path of movement as determined by the nozzle jet is followed more accurately, the less will be the chance of lag in the taking over of the weft by the auxiliary injector, and one will be permitted to be more critical with reference to the quantity of pressure fluid to be supplied to the nozzle. It has been found in practice that the behaviour of the weft in the jet issuing from the nozzle also depends on the nature ofthe weft and particularly on this being more or less fluffy or more or less twisted.

SUMMARY OF THE INVENTION According to the invention a device of the type above referred to is improved so that the behaviour of the weft may be influenced thereby and particularly so that irrespective of the nature of the thread the latter will have a stable positionin the nozzle jet and thereby an optimum taking over of the weft by the first auxiliary injector will be assured.

The device according to the invention is characterized in that the metering chamber is permanently in communication with the pressure fluid source and in that in said communication a control means is provided, by which the quantity of pressure fluid supplied with opened valve means is controllable independently of the quantity of pressure fluid supplied when the valve means is closed.

Said device makes it possible to have the primary quantity of pressure fluid necessary to yield the pulse for the acceleration of the weft, followed by a quantity of pressure fluid adjustable according to the nature of the weft, through the control means. This "after blowing of pressure fluid means that the weft is supported by the fluid during the complete transportation procedure.

In a preferred embodiment the valve means is constituted by a diaphragm movable between two seats in a valve chamber connected to the metering chamber, one seat communicating with the nozzle and the other seat being connectable alternately with the atmosphere and with the pressure fluid source through a control means. This embodiment has the advantage that the pulse shape is independent of the speed of operation of the weaving loom so that in particular when starting the weaving loom, immediately such a pulse is obtained that the first weft or wefts respectively will be moved with certainty through the shed within the available time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a diagrammatic view of the device according to the invention;

FIG. 2 shows the progress of the pulse acting on a weft launched by a nozzle jet in a known device and FIG. 3 shows the progress of the pulse acting on a weft to be launched by the nozzle jet when using the device according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIG. 1 a blowing nozzle or main injector of a known type is indicated by 1. This nozzle is connected by a passage 2 to a chamber 3 through a seat 4. The chamber 3 is formed in a housing 5 having a cover 6. There is a second seat 7 through which the diaphragm chamber 3 communicates with a control valve 9 through a passage 8.

In the diaphragm chamber 3 a diaphragm valve 10 is movable between the seats 3 and 7. Further a conduit 11 is connected to-the diaphragm chamber 3, in which conduit a reduction valve 12, a throttling valve 13 and a widened part 14 serving as metering chamber are provided. The conduit 11 is connected at the right-hand side of the reduction valve 12 to a pressure fluid source not shown in the drawing, e.g., a source of compressed air of 5 atm. The pressure of 5 atm. is reduced by the reduction valve 12 to a value of, e.g., 2 atm. A branch conduit 15 extends from a point in the conduit 11 between the valves 12 and 13 to the control valve 9.

The control valve 9 comprises a housing 16 and a spool 17 movable therein. The housing has three ports l8, l9 and 20, to which the conduit 8, the conduit 15 and a vent conduit 21 respectively are connected. The spool 17 is loaded by a spring 22 and controlled by a cam 23, the rotational movement of which is derived from the main shaft (not shown) of the weaving loom, the operative cam portion 23a corresponding to half a revolution of the main shaft during that portion of the weaving cycle in which the weft is introduced into the shed.

In FIG. 1 the device has been shown in the position in which the spool 17 takes the position in which the conduit 8 communicates via the port 18, the narrowed portion of the spool 17 and the port 19 with the conduit 15.

Thereby the diaphragm 10 is under the influence of the (reduced) feed pressure and said diaphragm is pressed onto the seat 4 so that the blowing nozzle 1 is not supplied with air and therefore inoperative. In the meantime the metering chamber 14 is supplied with air from two sides, viz, at one hand through the throttling valve 13 and at the other hand from the diaphragm chamber 3.

As soon as the operative portion 23a of the cam 23 has displaced the spool 17 of the control valve 9 against the spring 22 the device arrives in a position in which the spool 17 closes the port 19 whereas the ports 18 and 20 are mutually communicated through the narrowed portion of the spool 17, so that the conduit 8 is connected to the vent conduit 21. Thereby the pressure above the diaphragm is released and this results in the immediate flexing of the diaphragm 10 to the position shown with broken lines, in which the seat 7 has been closed and the seat 4 has been uncovered. The air volume collected in the metering chamber 14 up to the moment of flexing of the diaphragm 10 may now flow through the opened seat 4 along the passage 2 to the blowing nozzle 4.

In FIG. 2 the progress has been shown of the pulse which will be effected to the weft A by the quantity of air suddenly released during the first part of the weft path. Therein the high initial peak is essential to give the very high acceleration to the weft A which is necessary in order to have the weft cover the desired distance through the shed within the available time.

In the progress according to FIG. 2 the pulse has already been extinguished" long before the complete weft phase of 180 is ended. Such progress corresponds to a situation in which the supply to the metering chamber has been interrupted during the weft insertion. However, with the device as shown in the drawing the supply to the metering chamber 14 continues during that phase, namely through the throttling valve 13. This results in that the progress of the pulse has the appearance shown in FIG. 3. The hatched portion in FIG. 3 indicates the quantity of air which as compared to the situation according to FIG. 2 has the effect of being blown after. Said quantity of air blown after has a stabilizing influence on some types of wefts since said air ensures a better support for said weft types during the total insertion of the weft. The quantity of air blown after may be controlled at will by adjusting the throttling valve.

I claim:

1. A device for periodically supplying measured quantities of pressure fluid to a nozzle for blowing a weft thread into the shed of a pneumatic loom, comprising a metering chamber which is normally connected to a source of fluid under pressure, and a valve which connects the metering chamber to a blowing nozzle for discharging pressure fluid from the metering chamber, wherein the improvement comprises control means which opens the valve abruptly at the beginning of the weft-inserting portion of the weaving cycle to discharge the metering chamber and holds the valve open during the remainder of such portion of the weaving cycle, and a connection between the metering chamber and the source of fluid under pressure which admits a controlled afterflow of fluid to continue blowing fluid through the nozzle after the fluid stored in the metering chamber is discharged, the valve being formed by a diaphragm movable between two seats in a valve chamber in communication with the metering chamber, one seat being connected to the nozzle and the other seat being connectable by means of the control means alternately with the atmosphere and with the pressure fluid source. 

1. A device for periodically supplying measured quantities of pressure fluid to a nozzle for blowing a weft thread into the shed of a pneumatic loom, comprising a metering chamber which is normally connected to a source of fluid under pressure, and a valve which connects the metering chamber to a blowing nozzle for discharging pressure fluid from the metering chamber, wherein the improvement comprises control means which opens the valve abruptly at the beginning of the weft-inserting portion of the weaving cycle to discharge the metering chamber and holds the valve open during the remainder of such portion of the weaving cycle, and a connection between the metering chamber and the source of fluid under pressure which admits a controlled afterflow of fluid to continue blowing fluid through the nozzle after the fluid stored in the metering chamber is discharged, the valve being formed by a diaphragm movable between two seats in a valve chamber in communication with the metering chamber, one seat being connected to the nozzle and the other seat being connectable by means of the control means alternately with the atmosphere and with the pressure fluid source. 